Bunkers and mineral clearance boreholes

Circulation

Safety Circular - Reminder

Background

During the 1980's there were a number of fatal and other
accidents associated with underground vertical and inclined bunkers
and mineral clearance boreholes. The majority of these accidents
were due to the sudden and uncontrolled release of slurry, usually
during work aimed at releasing blockages. Most accidents involved
the mechanical failure of either bunker-bottom hoppers or discharge
side plates under the load of released material.

In 1989 HM Inspectorate of Mines looked in detail at the safe
operation of such bunkers and boreholes, and made a series of
recommendations accepted in full by mine owners, at that time
principally British Coal. Inspectors subsequently carried out a
series of inspections to identify the extent to which those
recommendations were being implemented at mines, and made a second
series of inspections to check on progress.

British Coal subsequently published an Operational Instruction
(OI/25) on 'Notes for Guidance for the preparation of a Code of
Practice for the Operation, Maintenance and Clearing of Blockages
of Underground Vertical Bunkers, Inclined Bunkers and Mineral
Clearance Boreholes', which incorporated Mines Inspectorate
recommendations.

Action

Although there have been no fatal accidents since that time
recent inspections have indicated that the knowledge and
implementation of control measures needs to be improved. The
hazards associated with bunker operations still persist, and mine
owners and managers must therefore ensure that they have in place
robust but practical measures to control risks to those who work in
the vicinity. Acting now will reduce the likelihood of further
incidents.

The principles and the detail within OI/25 are still the best
available source of recognised good practice guidance for coal and
non-coal mines alike.

Managers of mines with either underground vertical or inclined
bunkers, or mineral clearance boreholes, or surface bunkers, should
therefore review their procedures against the standard set out in
OI/25 and take steps to remedy any shortcomings.

Mines owners should ensure that the review is carried out to a
satisfactory standard and that the steps taken are appropriate.

The Mines Inspectorate will provide copies of OI/25 on request.
It can be freely photocopied thereafter.